Effect Of Light Environment On Photosynthetic Physiology And Root,Stem And Needle Anatomical Characteristics Of Naturally Regenerated Korean Pine Seedlings

The effect of shade on plant growth is a common concern in current research in plant ecology.Previous studies on shade have mainly focused on the changes of photosynthetic physiological characteristics of above-ground plant leaves,while the physiological characteristics of below-ground absorbing roots and stems have been less studied.In this paper,we studied the changes of photosynthetic physiological characteristics of needles,absorbing roots and stems of Korean pine seedlings under canopy dengsities of 0.2-0.3,0.4-0.6 and 0.8-0.9 conditions by taking full light condition as control.The following results were obtained:(1)Korean pine seedlings tired to maintain a high photosynthetic capacity by maintaining relatively low chlorophyll a/b values and high chlorophyll content under insufficient light conditions.(2)When Korean pine seedlings are in low light environment,they would allocate more NSC to stems and roots to accumulate in stems and improve themself survival rate.Korean pine seedlings are able to make corresponding strategies to the situation of lacking light resources,implying that Korean pine seedlings have strong adaptability to shade environment.(3)When the seedlings were in more adequate light conditions,their N was mainly concentrated in the needles while P in the stems.When the canopy density was 0.7-0.9,the N and P of needles would transfer to stems and roots.(4)The anatomical parameters of the roots,stems and needles of Korean pine seedlings showed the same changing pattern,reaching the highest values at canopy densities 0.4-0.6 and the lowest values of the anatomical parameters of each organ at canopy densities 0.7-0.9.The shade condition with canopy densities 0.4-0.6 was favorable for the growth and development of korean pine seedlings,and the overall growth of seedlings under shade condition with canopy densities 0.2-0.3 was also better than that of the control group of full light condition.When planting Korean pine under forest canopy,shading condition should be regulated to canopy densities 0.4-0.6,and Korean pine seedlings cultured in nursery should be properly shaded.